SPECTRAL ANALYSIS OF SPATIAL RAINFALL FIELD TO INVESTIGATE UNCERTAINTY IN HYDROLOGICAL MODELING

Abstract

The uncertainty in hydrologic model outputs is the accumulated effects of input data, model structure and process description, which all are also scale dependent features. It is hard to pinpoint the basic reason of uncertainty; however, it is understandable that the dominant reason remains changing on the basis of data type, model structure and parameterization over a range of scale. In this paper, the spatial rainfall structure has been analyzed by spectral observation over a wide range of spatial scale, which presents a good insight to understand the spatial rainfall structure dynamics. The scale dependency of spatial rainfall characteristic is detected as a dominant reason to impart uncertainty in larger scale relative to catchment scale. A significant sensitivity of reference grid position in multi scale frame is also noticed, which displays the extent of anisotropic rainfall structure and its effect on different scale. The Huaihe River basin (132, 350 km²) and its sub-basins are taken as a case study.